Duet
Part of speech: verb
Definition: To perform a duet. To communicate (warnings, mating calls, etc.) through song.
Part of speech: noun
Definition: A musical composition in two parts, each performed by a single voice (singer, instrument or univoce ensemble). A pair or couple, especially one that is harmonious or elegant.
Example sentence: I'd rather be onstage with a pig - a duet with Jennifer Lopez and me just ain't going to happen.
Duo
Part of speech: noun
Definition: A twosome, especially musicians
Example sentence: I'm a twin, but only I emerged live from the womb. The fact that I was originally one half of a duo gave rise to a theory, much propounded in newspaper profiles, that my life has been one desperate effort to compensate for that stillborn brother.